Function update 

pub fn update(
    layout: &Layout,
    id: &str,
    new_state: Option<&str>,
    new_priority: Option<char>,
    block_add: Option<&str>,
    block_clear: Option<&str>,
) -> Result<UpdateOutcome>

Change state, priority, or blocker edges. Adding a blocker to an open issue moves it to BLOCKED; clearing the last blocker moves it back to TODO.

Errors

Returns an error if id is not in the corpus, the state or priority is invalid, adding the blocker would cycle, or the file cannot be rewritten.